High data reliability, high speed of memory access, lower power consumption and reduced chip size are features that are demanded from semiconductor memory. One of defects that lowers the data reliability is a breaking in a wire for Y-address (e.g., a column address) selection (YS). The breaking in the wire for Y-address tends to be undetected in a post-manufacturing test.
Techniques to remedy the disconnection due to the broken wire have been introduced to the semiconductor memory. For example, redundancy wires for address lines have been introduced to replace the broken wires, which improve data reliability of the semiconductor memory. A Y-address selection line (YS) driver does not activate the broken wire. In some cases, a signal disconnection occurs in proximity to a location where the wire may be broken. The broken YS wire is divided into two parts, one part connected to the YS driver and the other part not connected to the YS driver. The other part not connected to the YS driver is in an electrically floating state that is not stable and takes any voltage level, including a logic high level of the Y-address wire indicative of an “ON” state. As a result, a data on a local input/output line can be overwritten by the “ON” state signal due to the electrically floating state of the other part of the broken YS wire.